The invention relates generally to the field of digital data networks and more particularly to networks in which digital data is transferred using wavelength division multiplexing techniques. The invention particular provides an arrangement providing a control channel for carrying control information for use in network management and controlling operations of various nodes connected in such wavelength division multiplexing (xe2x80x9cWDMxe2x80x9d) networks.
Digital data networks are used to transfer data and other information among a plurality of devices, such as computers for processing, mass storage subsystems for storage and retrieval, connections to other networks such as the public telephony system and the like. As networks become larger, and with ever increasing numbers of devices being connected therein for transmitting and receiving information, the demand for information transfer bandwidth increases correspondingly. Since light beams have a higher information carrying capacity than electronic signals, optical information transfer techniques, in which information is transferred using beams of light through optical fibers are being increasingly used. In addition, since optical fibers can typically carry light beams of many different wavelengths concurrently, wave-division multiplexing techniques, in which information is transferred through a single optical fiber using a plurality of beams of light concurrently, are being employed to further increase the bandwidth.
A problem arises, however, in connection with use of light beams in information transfer. As is conventional, typically nodes in a network need to have various aspects of their operation be observed and controlled by, for example, a network administrator. Of particular interest in connection with nodes connected in a network in which information is transferred using light beams, the particular wavelengths that a node uses to communicate with other nodes, and the power of the light beams that are used, also need to be controlled. A special control console connected to all of the nodes over respective direct connections could be provided, but that would also increase the cost of the network. To avoid that, one of the nodes in the network can be provided with control console capabilities, but a mechanism is also needed by which that node transfers the control information to the other nodes in the network. If optical fibers are used to transfer the control information, generally each node, when it receives the light beam comprising the control channel, regenerates the light beam before transferring it to another node in the network, with the regeneration mechanisms increasing the cost of the node.
The invention provides a new and improved system and method for providing a control channel in a network in which digital data is transferred using wavelength-division multiplexing techniques.
In brief summary, in one aspect, the invention provides a network including a control channel source node and a plurality of control channel destination nodes interconnected by an optical fiber communications medium, the control channel source node and control channel destination nodes transferring information over a plurality of channels using wavelength-division multiplex techniques. The control channel source node transmits a light beam comprising the control channel to the control channel destination nodes over a unitary control channel. As each control channel destination node receives the light beam comprising the control channel, it drains off a portion of the energy of the light beam to facilitate decoding and processing of the control information contained therein. Generally, each control channel destination node will also transfer the remaining portion to another node, which may be either another control channel destination node or the control channel source node.
In another aspect, the invention provides a control channel source node for use in a network in which information is transferred using wavelength-division multiplexing techniques. The control channel source node generates a light beam comprising the control channel for transfer to other nodes, operating as control channel destination nodes, to transfer control information thereto over a unitary control channel.
In yet another aspect, the invention provides a control channel destination node for use in a network in which information is transferred using wavelength-division multiplexing techniques. The control channel destination node receives control information over a control channel generated by a control channel source node, and drains off a portion of the energy of the signal comprising the control channel to facilitate decoding and processing of the control information contained therein.
In further connection with each of the aspects, the control channel destination node(s) can also generate status information for transfer to the control channel source node over the control channel. The control channel source node drains off the energy of the signal comprising the control channel to facilitate decoding and processing of the status information contained therein.